In a conventional vehicle navigation system, the calibration of the length measurement of a wheel sensor is based upon driving along a path of known distance. This calibration method requires, however, that the length of the calibration path be exactly known and that the path be driven along exactly (from beginning to end), in order to minimize length measurement errors. This procedure is necessary after initial installation of the navigation system in the vehicle, or when a tire change is made (such as, for example, after a changeover from summer to winter tires, or from old to new tires). In the situations described above, it is therefore necessary to have the displacement sensor length measurement calibrated at the repair shop.